Necticut



Reisauecl Dec. 13, 1932 UNITED STATES PATENT OFFICE WILLIS A. GIIBBONS,OF MONTCTLAIR, NEW JERSEY, ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY,OF NA'UGATUCK, CONNECTICUT, A CORPORATION OF CON- NECTICUT' PROCESS FORMODIFYING VULCANIZABLE MATERIAL AND PRODUCT No Drawing. Original No.1,807,031, dated May 26, 1931, Serial No. 174,716, filed March 11, 1927.

Application for reissue filed March 30, 1932. Serial No. 602,104.

This invention relates to a process for modifyin r vulcanizable materialand to the product thereof more particularly to a process for modifyingthe physical properties of the material and its product.

In the manufacture of rubber articles the raw rubber used comes frommany sources, is obtained from the latex in various ways and isvariously treated to adapt it for different uses. For instance there areplantation rubbers obtained from the latex by different c0- agulationmethods in which all or a greater part of the soluble contents of thelatex have been eliminated, wild rubbers from which a greater or lesspart of the soluble constituents of the latex have been removed, andall-solidcontent latex rubbers obtained by the direct drying of latex.Aside from cleaning operations where necessary, the usual preliminarystep is to break down the crude rubber on heated rolls, after which itmay be compounded and used in plastic form or treated with organicsolvents for spreading or dipping operations. Recently there has beenconsiderable use of latex direct for spreading, dipping and similarpurposes. The various rubbers as obtained from the latex varyconsiderably in their properties, such as break down period, ageing,elasticity, tensile strength, viscosity, softness, optimum curing time,etc., and as a result one of them may be most suitable for a certain usewhile another is best adapted for some other purposes. For instance theall-solid content latex rubber has great strength, superior ageing andcuring qualities and elasticity, but ordinarily requires a longerbreakdown period than certain other rubbers. It will therefore be seenthat it is often desirable to impart to one variety of crude rubberproperties possessed by another while at the same time retaining certainof its own distinguishing characteristics. It is obvious that by somodifying the properties of one rubber stock it may be made to serve fora greater number of purposes, with resulting increased efiiciency andeconomy. It has also been found that articles or materials obtained bydirect deposition of rubber from latex, as by spreading or dipping, evenwhen vulcanized are stiffer or more inflexible modifying the millingproperties of crude rubber.

Still another object is to provide a process for modifying the physicalproperties of vulcanizable or vulcanized articles or materials, pbtainedby direct deposition of rubber from atex.

A further object is to increase the fieldof usefulness of individualcrude rubbers in'the rubber art.

A still further object is to provide a crude rubber having a reducedbreak down period.

A still further object is to provide a vulcanizable or vulcanizedmaterial, derived directly from latex, and having an increasedflexibility.

The invention consistsbroadly in modifying the properties of vulcanizable material, particularly its physical properties, by preliminarilysubjecting latex to regulated heat and pressure, with or without theassistance of chemicals, and it also consists in the product of theprocess.

For a detailed disclosure of the invention reference is had to theaccompanying specification.

In carrying out one embodiment of the invention in the case of avulcanizable material such as rubber, rubber latex is disposed in aclosed vessel or tank in quantity suflicient almost to fill the same,and is then subjected to heat, and to pressure such as that resultingfrom the heating. This heating may be accomplished in any suitablemanner, as by using a steam jacketed tank. The heat may be applied ingradually increasing degree for a definite period, or after such gradualheatcrepe is shown in the following data taken from a series of tests:

' Break Power Heating conditions [or preliminarily treated. downconall-solids content-latex rubber time sitrmpion Kilowatt l M'imztesh'our hr. rise to 20# steam 7% 0958 $5 hr. rise to 201! 1 hr. at 20# 60696 hr. rise to 20# 1 hr. at 20# 8 .0895 6 hr. rise to 60;! 7 .0841 60695 56 hr. rise to 60# 1 hr. at 60#- 6% 0722 )6 hr. rise to 60# 3 hrs.at 60# l. 5 Ordinary all-solids content latex rubber 10-11 1308 Palecrepe .7 7% 0977 The latex rubbers referred-to in the above table wereobtained by spray drying of the latex, but the invention is not,however, limited to rubber obtained from the latex by any particularmethod. It is known'to sterilize latex at 212 F. under pressure. Suchprocedure, however, is a brief one and it will :be apparent from theabove table that the treatment in this case is in excess of such atreatment in order to have the desired effect upon the rubber ratherthanon the germs present in the latex. V o

In addition to the heat treatment above described the'process may alsoinclude the use as for example derivatives of hydroxylamins.

or hydrazines. The invention also includes treating latex withsubstances adapted to alter the properties of the rubber hydrocarboneither chemically or physically, but excluding vulcanization, as forexample rubber solvents or softeners or substances adapted to oxidizerubber, such as drying oils and/or oxidizing agents. These materials mayif desired be added to the latex in the form of emu sions.

The preliminarily treated latex may be used directly for such operationsas dipping or spreading, and it has been found that the material orarticles formedin this manner have a greatly increased flexibility,whileat the same time retaining all the desirable-qualities obtained bythe use of untreated latex. If desired the preliminarily treated latexmay be concentrated in the usual manner, and the concentrated latex usedas desired with the same good results as obtained in the case ofunconcentrated treated latex. The treated latex may also be convertedinto crude rubber by any of the standard methods, which rubber hasbeen-found to be considerably softer and to have a shorter breakdownperiod. The treated latex may be sprayed directly from the vessel inwhich it has been heated under pressure. By running the latex whilestill hot into the spray chamber the heat content of the latex may thusbe utilized and an economy in manufacture effected. It might be supposedfrom previous knowledge of the characteristics of rubber that the abovedescribed treatment for increasing the softness and reducing thebreakdown period of the rubber would result in a corresponding decreasein the tensile strength and deterioration in its other physicalproperties, but such has not been found to be the case. For in stancethe time of cure and the tensile strength of spray dried rubber,produced from the heat treated latex has been found to be practicallythe same as, and in some cases superior to, that produced from spraydried unheated latex. a

. It will'be seen that by my invention the field of use for anindividual crude rubber maybe considerably enlarged by modifying itsproperties to adapt it for purposes for which another rubber stock mayhave been primarily more suitable, thus enabling rubber factories toreduce the number of different stocks required for various purposes. Inparticular the reduction in the breakdown period from the normal onerequired with a similar rubber made from untreated latex constitutes avaluable saving both in the time, labor and space required, and also inthe power consumption. The increased flexibility of goods obtained bythe direct deposition of rubber from the treated latex is also anothervaluable feature of the invention. I

While the invention has been more or less specifically described it isobvious that the present disclosure will suggest numerous modificationsto those skilled in the art and it is not desired to limit the inventionotherwise than as set forth in the appended claims.

. Having thus described my invention, what I claim and desire to protectby Letters Patent is: v

1. The process of modifying the properties of vulcanizable material bypreliminary treatment'of latex with normal water content which. processcomprises heating the latex above 212 F. without evaporation of itswater content for a length of time in excess of that required tosterilize latex against the action of bacteria.

2. The process of modifying the properties of vulcanizable material bypreliminary treatment of normal latex which comprises gradually raisingthe temperature of the latex to a. predetermined point above 212 F.while contained in a closed vessel, and maintaining it at such point forabout one-half to three hours.

3. The process of modifying the milling properties of vulcanizablematerial which consists in subjecting latex of normal water content to aregulated heat and pressure at a temperature above 212 F. for at least ahalf hour while simultaneously maintaining its water contentsubstantially unchanged, and subsequently withdrawing water therefrom.

4. The process of modifying the physical properties of vulcanizablematerial by preliminary treatment of normal latex which comprisessubjecting the latex without coagulation, precipitation to its solids orsubstantial change in its water content, to the action of chemicalsunder gradually increasing heatand pressure to above 212 F. for a lengthof time in excess of that required to sterilize latex against the actionof bacteria.

5. A method of treating an aqueous dispersion of rubber comprisingsubjecting a rubber latex in the absence of vulcanizing agents to anelevated temperature without substantial evaporation of the watercontent for a length of time in excess of that required to sterilizelatex at such temperature against the action of bacteria.

6. A method of treating an aqueous disper sion of rubber comprisingsubjecting a rubber latex in the absence of vulcanizing agents to a.temperature above 212 F. for at least a half hour without substantialevaporation of the water content.

7. A method of treating an aqueous dispersion of rubber comprisingsubjecting a rubber latex in the absence of vulcanizing agents to atemperature above 212 F. for a length of time in excess of that requiredto sterilize latex against the action of bacteria. v

8. A method of treating an aqueous dispersion of rubber comprisingsubjecting a rubber latex treated with a non-vulcanizing modifyingreagent to an elevated temperature with out substantial evaporation ofthe water content thereof for a period of time sutficient to permit theconversion of water-in soluble nonrubber constituents into water-solubleprodnets.

9. A method of treating an aqueous dispersion of rubber comprisingsubjecting a rubber latex in the presence of a substance adapted tocombine with or decompose a non-rubber constituent of the latex to a.temperature above 212 F. for a length of time in excess of that requiredto sterilize latex against the action of bacteria Without substantialevaporation of the water content thereof.

10. A method of treating an aqueous dispersion of rubber comprisingheating at an elevated temperature fora period oftime in excess of thatrequired to sterilize latex against the action of bacteria at suchtemperature, a rub-ber latex in the presence of a substance adapted todecompose proteins in" the latex and without substantial reduction ofthe water content thereof.

11. A method of treating an a ueous dispersion of rubber comprising sujecting a rubber latex in the presence of caustic alkali to atemperature above 212 F. for at least a half hour without substantialevaporation of the water content.

12. The process of modifying the properties of vulcanizable materialwhich comprises subjecting a rubber latex treated with a nonvulcanizingmodifying reagent to an elevated temperature for a period of timesufficient to permit the conversion of water-insoluble non-rubberconstituents into watersolub-le products and subsequently recoveringrubber from the thus treated latex.

13. The process of modifying the properties of vulcanizable materialwhich comprises subjecting a rubber latex in the presence of a substanceadapted to decompose a non-rubber constituent of the latex to anelevated temperature for a predetermined period of time withoutsubstantial decrease of the water content of the latex, and subsequentlyrecovering rubber from the thus treated latex.

14. The process of modifying the properties of vulcanizable materialwhich comprises subjectin a rubber latex in the presence of causticallxali to an elevated temperature for -mo a. predetermined period oftime, and subsequently recovering rubber from the thus treated latex.

15- The process of modifying the properties of vulcanizablematerial'which comprises subjecting a rubber latex to an elevatedtemperature without substantial evaporation of the water content for alength of time in excess of that required to sterilize latex against theaction of bacteria at such temperature, and subsequently recoveringrubber material from the thus treated latex.

16. The process of modifying the properties of vulcanizable materialwhich comprises subjecting a rubber latex in the presence of a substanceadapted to decompose a non-rubber constituent of the latex to atemperature above 212 F. for at least a half hour without substantialevaporation of the water content, and subsequently recovering rubber ma-12o terial from the thus treated latex.

17 The process of modifying the properties of vulcanizable materialwhich comprises heating a rubber latex above 212 F. for at least a halfhour without substantial evaporation of the water content andsubsequently recovering rubber material from the thus treated latex.

18. As a new article of manufacture, a rubber product obtained frommodifying normal 'York, and State of New York, this 29th day latex byheat and pressure at a temperature above2l2 F. without substantialchange in the water content for a length of time in excess of thatrequired to sterilize latex against the action of bacteria.

' 19. As a new article of manufacture, a vulcanizable rubber productobtained from modifying normal latex by the action of chemicals and heatand pressure at a temperature above 212 F. for at least one-half hour,said product having increased softness and reduced viscosity. 2 p

. 20. As a new 7 article of manufacture, a modified crude rubberobtained from heating normal latex under heat and pressure at atemperature above 212 F. for one-half to three hours and having asub-normal breakdown period and increased flexibility.

21. As. a new product, a rubber latex heated in the absence ofvulcanizing agents at an elevated temperature without substantialevaporation of the water content for a length of time in excess of thatrequired to sterilize against the action of bacteria at such elevatedtemperature.

22. As a new product, a rubber latex heated in the absence ofvulcanizing agents above 212 F. for at least a half hour withoutsubstantial evaporation of the water content;

23. As a new article of manufacture, a rubber product obtained from alatex treated with a non-vulcanizing modifying reagent, and subjected toa temperature above 212 F. for at least a half hour without substantialevaporation of the water content.

'24. As a new product, a rubber latex heated in the absence ofvulcanizing agents above 212 F. without substantial evaporation of thewater content for a length of time in excess of that required tosterilize latex against the action of bacteria.

25; As a new article of manufacture, a rubber product obtained fromheating a latex at a temperature above 212 F. for a length of time inexcess of that required to sterilize latex against the action ofbacteria without substantial change in the water content thereof. i

Signed at New York, in the county of New of March, 1932.

WILLIS A. GIBBONS.

